This invention relates to a printing apparatus and facsimile apparatus using the printing apparatus and, more particularly to a printing apparatus that performs printing in accordance with an ink-jet printing method and facsimile apparatus using the printing apparatus.
Conventionally, printers that perform printing in accordance with an ink-jet printing method employ various techniques as described below to detect the amount of residual ink in their ink tank.
Japanese Patent Application Laid-Open No. 2-102061 discloses a reflective type photosensor, with a reflection board provided in an ink tank, to detect shortage of ink. In Japanese Patent Application Laid-Open No. 56-144184, to avoid degradation of detection precision due to ripples of the ink surface, ink shortage status is notified after a predetermined period from detection of the status.
Further, a control method utilizing a photo-interruptive type sensor with an electrode provided in an ink tank is known. An electric signal which varies in accordance with change of residual-ink amount is obtained from the sensor, and if it is determined in accordance with the detected signal that the ink is exhausted, immediately print operation is stopped.
However, in the above conventional art, since a photosensor is used for the residual-ink detection, temporary impingement of external light such as sunlight or intense spot light on a photoreceptor of an residual-ink detection sensor causes erroneous determination of ink shortage.
Further, for the residual ink detection, to detect a photosensor output, the above prior art uses a circuit which requires adjustment due to fluctuation of the sensor output, the secular change of sensor characteristic, and variation in sensing mechanism, which exceed allowable values. Further, as the ink cartridge itself trembles due to vibration of the apparatus or the like, noise may be mixed in the residual-ink detection, otherwise, the sensor output varies due to ripples of the ink surface, thus degrading the precision of residual-ink detection.
Further, the conventional residual-ink detecting technique has a drawback that it cannot detect status where the ink is completely exhausted. For example, as a typical conventional art, in an ink tank containing a sponge at an internal portion for preventing ink leakage, ink is first supplied to the sponge from an ink reservoir portion, and the ink is supplied to a printhead from the sponge fully containing the ink. In this ink tank, the amount of ink contained in the sponge cannot be detected by the aforementioned techniques.
Accordingly, in the above control method, since the print operation is stopped even when ink remains in the sponge, the residual ink in the sponge cannot be used for printing.
To solve this problem, an apparatus which performs print control so as to perform ink discharge while counting the number of dots after it is determined that ink is exhausted, and continue printing until the counted number of dots becomes a predetermined value (this is referred to as "further-discharging control"), has been proposed.
However, this construction cannot be applied to an apparatus having a suction-recovery mechanism that performs periodical or intermittent sucking on nozzles by a pump or the like to prevent ink clogging, unless the amount of ink consumed by this suction recovery is considered.